How to Fix a Kitchen Sink That Won’t Drain Properly

Post By Admin

February 18, 2025

If your kitchen sink won’t drain, built-up grease, food scraps, or even a hidden plumbing issue could be to blame.

Ignoring it might make things worse—hello, bad smells and overflowing water! But don’t worry, there are simple ways to get things moving again. 

And if nothing seems to work, calling a blocked drain service might be your best bet. Let’s break down the reasons—and how to fix them!

5 Reasons Why Your Kitchen Sink is not Draining

Sometimes, the cause isn’t always obvious. Here’s what might be blocking your kitchen sink drain:

1. Grease and Fat Buildup

Ever poured leftover cooking oil or grease down the drain? It may seem harmless at first, but as it cools, it solidifies and sticks to the inside of your pipes. 

Over time, this creates a sticky blockage that traps food particles and other debris. 

A key sign? Water drains slowly at first, then stops altogether. 

If you notice a smelly sink, that’s also a red flag—rotting food caught in the grease buildup can create a nasty odour.

2. Food Scraps and Debris

Even with a sink strainer, tiny food particles can slip through and pile up in your pipes.

Starchy foods like pasta and rice expand with water, making things worse. And let’s not forget coffee grounds—they clump together and form a solid mass. 

If your sink is not draining after washing dishes, food waste could be the culprit. You might hear gurgling sounds as trapped air struggles to escape.

3. Soap Scum and Mineral Deposits

Living  in an area with hard water? Minerals from your tap can build up inside your pipes, slowly narrowing the passage for water to flow. 

Soap scums make things worse by sticking to those mineral deposits, creating a stubborn clog. 

That’s why, if your sink won’t drain but you don’t see any obvious food debris, hard water buildup could be at play. A chalky white residue around your drain is a telltale sign.

4. Clogged or Damaged P-Trap

The P-trap is the curved pipe under your sink that prevents sewer gases from coming up. 

Unfortunately, it’s also a common spot for blockages. Grease, food scraps, and small objects can collect here, blocking water flow. 

Say, you have a leaking kitchen sink pipe. Pay attention to leaks under the sink along with standing water since it can cause both drainage problems and water damage.

5. Main Drain Line Blockage

If you’ve tried everything and nothing works, the problem might not be in your kitchen—it could be deeper in your home’s plumbing system. 

A blocked main drain line can affect multiple sinks and even cause water to back up elsewhere. 

A slow draining kitchen sink  is annoying, but knowing the cause is half the battle. Now that you know what might be clogging your pipes, let’s look at how to fix it!

6 Ways to Fix a Sink that Won’t Drain

Whether it’s grease, food scraps, or a deeper blockage, there’s a fix for every situation. Let’s go step by step!

1. Pour Boiling Water

Boiling water works well for grease and soap buildup. Please note: only use this method for metal pipes. If you have PVC pipes, extreme heat can weaken or damage them.

1. Boil a kettle of water.
2. Slowly pour it down the drain in stages.
3. Wait a few minutes, then check if the water drains.
4. Repeat if necessary.

2. Use a Plunger

A plunger can create enough suction to dislodge blockages. Here’s how:

1. Fill the sink with a few inches of water.
2. Place a cup plunger over the drain, ensuring a tight seal.
3. Pump vigorously for 15–20 seconds.
4. Lift the plunger and see if the water drains.
5. Repeat if needed.

If plunging improves the drainage but doesn’t fully clear it, you might want to try the next method.

3. Try Baking Soda and Vinegar

Using baking soda and vinegar is a natural and effective way to break down debris, clear minor clogs, and maintain your kitchen sink pipes:

1. Pour half a cup of baking soda into the drain.
2. Add one cup of vinegar.
3. Let the fizzing reaction work for 15 minutes.
4. Rinse with hot water to flush out the loosened debris.

4. Check and Clean The P-Trap

Cleaning the P-trap is a simple yet effective way to restore proper water flow and eliminate odors:

1. Place a bucket under the P-trap to catch water.
2. Unscrew the slip nuts and remove the P-trap.
3. Check for blockages and rinse it out.
4. Reattach the P-trap securely and run water to test the drain.

5. Use a Drain Snake

A drain snake is especially useful when baking soda, vinegar, or P-trap cleaning doesn’t fully resolve the issue. 

The flexible metal cable can navigate through bends and dislodge blockages like grease, food particles, and other debris that accumulate over time.

1. Insert the snake into the drain opening.
2. Turn the handle while pushing it further down.
3. When you feel resistance, rotate it to break up the blockage.
4. Pull it out and dispose of any debris.
5. Run water to check if the sink drains properly.

6. Fix a Leaking Pipe

A leaking pipe can also contribute to drainage problems by reducing water pressure or creating standing water that slows down proper flow. In this case, follow these steps:

1. Check the pipes for cracks, loose connections, or worn-out seals.
2. Tighten loose fittings with a wrench.
3. Apply plumber’s tape to small leaks or use a pipe clamp for temporary fixes.
4. If the pipe is severely damaged, replace the section or call a professional plumber.

How to Keep Your Kitchen Sink from Clogging Again

Preventing clogs is easier than dealing with them. Start by being mindful of what goes down the drain. 

Avoid pouring grease, oil, or fat, as they solidify and cause blockages. Instead, collect them in a container and dispose of them properly. 

Use a sink strainer to catch food scraps, coffee grounds, and other debris before they enter the pipes. 

Flush the drain weekly with hot water or a baking soda and vinegar mix to break down buildup. Last but not least, check under the sink regularly for leaks or loose fittings.

FAQ about Kitchen Sink that Won’t Drain

1. Why is my sink not draining but not blocked?

If your sink drains slowly but isn’t fully blocked, the issue could be grease buildup, soap scum, or mineral deposits restricting water flow. 

A partially clogged P-trap or venting problem could also be the cause. Try flushing with hot water or using a drain snake to clear any hidden debris.

2. Will a clogged sink eventually drain?

It depends on the severity of the clog. 

A minor blockage might allow water to drain slowly, but a serious clog won’t clear itself and can get worse over time. 

It’s best to fix it early before it leads to a full blockage

3. How do plumbers unclog sink drains?

Plumbers use tools like drain snakes, augers, and hydro jets to remove tough clogs. 

They may also disassemble the P-trap or use cameras to inspect deeper blockages. 

Conclusion

A kitchen sink won’t drain for many reasons, from grease buildup to deeper plumbing issues. 

The good news? Many clogs are easy to fix with simple tools and proper maintenance. 

Contact Neighbourhood Plumbing for fast and reliable drain-clearing services. Our experts will get your sink flowing smoothly again in no time!

About the Author

Ricky Rizz

From unclogging the toughest drains to repairing leaking toilets, Ricky is a seasoned plumber who has brought his craftmanship to homes across Melbourne. He is passionate about sharing plumbing tips just as much as he is about fixing your plumbing issues. So, when your taps or pipes begin leaking, you know who to call.